In general, you have two choices when creating a wiki. The first choice, and the one that is most appropriate to this forum, is to create a 'hosted wiki' and the second choice is to download and install your own wiki. Hosted wikis are a good place to experiment and get started and depending upon your needs, you might find that you don't need anything else. For larger organisations or for tighter control and security, many people chose to install their own wiki on their Intranet.

Hosted Wikis

Hosted wikis are wikis that are run and maintained by companies online, they generally easy to set up and use. There are free hosted wikis and commercial ones too, and in general the features available will vary depending upon how much you spend. As an example, this wiki is free, so there is some advertising and some limitations to it's use.

The following table lists some good hosted wiki options

Wikispaces	Wikispaces provide a good free wiki service. More features are available for a small montly charge.	To create a wiki, using wikispaces, see the tour at http://www.wikispaces.com/site/tour#introduction, or follow the instructions from the home page at http://www.wikispaces.com/
PB Wiki	PB Wiki is another very good wiki	See http://pbwiki.com/

Wiki Software

The second choice for creating a wiki is to install your own wiki. Just like hosted wikis, there are many different options available, both free and commercial. You can even install a wiki on your own computer and use it a 'personal wiki'. There are literally dozens of wikis available and each has its own strengths and weaknesses depending upon your organisation's environment and the particular features you need. You can see comparisons of the major wikis at http://www.wikimatrix.org/